Cannabis produces a complex suite of bioactive compounds, including tetrahydrocannabinol (THC) and cannabidiol (CBD), but how these molecules evolved has long been a mystery. Now, new research has shed light on their origin story – and opened the door to innovative ways of harnessing these compounds for human medicine.

Researchers at Wageningen University & Research (WUR) in the Netherlands have experimentally traced how cannabis evolved the ability to synthesize THC, CBD and another major cannabinoid, cannabichromene (CBC), revealing new insights into the plant’s evolution and how we can harness its power.

In modern cannabis varieties, the proportions of these cannabinoids vary widely and are largely determined by the activity of corresponding synthase enzymes. The enzymes are also highly specialized products of a long evolutionary process and today’s types are far removed from those that existed millions of years ago.

Using ancestral sequence reconstruction, which reconstructs ancient proteins from modern genetic data, the team resurrected cannabinoid-producing enzymes from early cannabis ancestors. When expressed in the lab, the enzymes revealed which cannabinoids they could produce – and how their activity differed from modern versions.

What they found was that, unlike today’s highly specialized enzymes that produce specific cannabinoids, these ancient types were generalists, capable of creating multiple compounds – including THC, CBD and CBC – from a common precursor.

“What once seemed evolutionarily ‘unfinished’ turns out to be highly useful,” said WUR researcher Robin van Velzen, who led the study with his colleague Cloé Villard. “These ancestral enzymes are more robust and flexible than their descendants, which makes them very attractive starting points for new applications in biotechnology and pharmaceutical research.”

Of particular interest to the researchers, and to medicine more broadly, are the findings related to CBC. While most research into cannabis compounds has focused on THC and CBD, CBC is emerging as a potentially important but underexplored cannabinoid. Modern cannabis plants typically contain less than 1% CBC, making it difficult to study and produce at scale.

“At present, there is no cannabis plant with a naturally high CBC content,” said van Velzen. “Introducing this enzyme into a cannabis plant could therefore lead to innovative medicinal varieties.”

Preliminary studies have suggested that CBC has anti-inflammatory, anticonvulsant and antibacterial properties, among others, although its therapeutic potential remains far less studied than THC or CBD.

The team also found that the reconstructed ancestral enzymes were easier to produce in micro-organisms, such as yeast cells, than modern-day types, which mean they can be harnessed to synthesize cannabinoids more efficiently. This raises the possibility of producing rare cannabinoids without relying on plant cultivation, with implications for both research and drug development.

“Through rational engineering of these ancestors, we designed hybrid enzymes which allowed identifying key amino acid mutations underlying the functional evolution of cannabinoid oxidocyclases,” the team wrote. “Ancestral and hybrid enzymes also displayed unique activities and proved to be easier to produce heterologously than their extant counterparts. Overall, this study contributes to understanding the origin, evolution and molecular mechanism of cannabinoid oxidocyclases, which opens new perspectives for breeding, biotechnological and medicinal applications.”

The study was published in the Plant Biotechnology Journal.

Source: Wageningen University & Research